A reflection target-holding device which holds a reflection target (prism, for example) on a supporting member (pole, for example), and a survey machine for measuring a distance based on distance-measurement rays which are input to and reflected from the reflection target are used for measurement. In the measurement using these, the survey machine measures a vertical angle, a horizontal angle and a distance-measurement value on the center of the reflection target, and the survey machine further calculates, by using these measurement values, the information about a position identified by the reflection target-holding device (a point where the supporting member is in contact).
As described in Patent Publication 1 (FIG. 3), a survey machine has been widely used that includes functions of automatically collimating the reflection target of the reflection target-holding device, and of chasing the reflection target of the reflection target-holding device. When these functions are achieved and a plurality of the reflection targets are detected in an angular field of the survey machine's telescope, the reflection target nearest to the telescope center is locked (automatically collimated). When no reflection target exists in the angular field of the telescope, the vertical angle and the horizontal angle are adjusted to search the circumference for locking the reflection target which is located first.
These functions are focused, and the reflection target-holding device is mounted on a ground-leveling vehicle (grader, for example) on a working site where the leveling of the working surface such as a road surface is performed. By means of the full-time observation of the measurement values of the reflection target based on the functions of the automatic collimation and the automatic chasing, the leveling situation of the working surface is comprehended for intending the optimization of the working (planarization of road surface).
In the measurement work by a measurement worker, while the worker moves the reflection target-holding devices to many measurement points, the reflection target of the reflection target-holding device is automatically chased to the survey machine so that the information of the respective measurement points is obtained. Based on the information, the leveling situation of the working surface is comprehended.